Wenceslaus I (also Wenceslas, Venceslas, Wenzel, or Václav, often called Wenceslaus of Bohemia in chronicles) was the first Duke of Luxembourg from 1354. He was the son of John the Blind, King of Bohemia, and Beatrice of Bourbon.
In 1353 Charles IV King of Bohemia, Count of Luxembourg and elected Holy Roman King, entrusted the county, their father's inheritance, to his half-brother Wenceslaus. In 1352, Wenceslaus married Joanna, daughter of John III, Duke of Brabant and Limburg, and Marie d'Évreux. In 1354 Charles raised Luxembourg to the status of a duchy. In 1355, Joanna inherited Brabant and Limburg. In order to guarantee the indivisibility of Brabant, Wenceslaus signed the Joyous Entry, but had to fight against his brother-in-law Louis II of Flanders, who asserted his share of the duchy.
Wenceslaus died in Luxembourg, leaving Joanna as sole ruler of Brabant, and was succeeded by Wenceslaus II (Wenceslaus IV of Bohemia) as duke of Luxembourg.